Tolterodine and Clarithromycin Interaction
Drug interaction information between Tolterodine and Clarithromycin.
Tolterodine and Clarithromycin have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Tolterodine and Clarithromycin. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Clarithromycin stops the body from breaking down tolterodine, leading to higher levels of the drug in your system. This is more likely to happen if your body already processes certain medicines slowly.
What To Do
Your doctor should lower your tolterodine dose to 1 mg twice a day if you are taking these together.
FDA Label Information
Lurasidone: [See Contraindications ( 4.7 )] Antispasmodics: Tolterodine (patients deficient in CYP2D6 activity) Use With Caution Tolterodine: The primary route of metabolism for tolterodine is via CYP2D6. In this population subset, inhibition of CYP3A results in significantly higher serum concentrations of tolterodine. Tolterodine 1 mg twice daily is recommended in patients deficient in CYP2D6 activity (poor metabolizers) when co-administered with clarithromycin.
Tolterodine Also Interacts With
- Omeprazole minor
- Hydrochlorothiazide minor
- Fluoxetine minor
- Furosemide minor
- Estradiol minor
Clarithromycin Also Interacts With
- Quetiapine major
- Pioglitazone major
- Fluconazole major
- Cyclosporine major
- Lurasidone major
Frequently Asked Questions
Can I take Tolterodine and Clarithromycin together?
This is a moderate interaction. Your doctor should lower your tolterodine dose to 1 mg twice a day if you are taking these together.
How serious is the interaction between Tolterodine and Clarithromycin?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Tolterodine and Clarithromycin interact?
Clarithromycin stops the body from breaking down tolterodine, leading to higher levels of the drug in your system. This is more likely to happen if your body already processes certain medicines slowly.
Understanding the Tolterodine and Clarithromycin Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Tolterodine belongs to the Anticholinergic (Overactive Bladder) class and Clarithromycin belongs to the Macrolide Antibiotic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Clarithromycin stops the body from breaking down tolterodine, leading to higher levels of the drug in your system. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Tolterodine has 15 total documented interactions on file in this dataset, and Clarithromycin has 81. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Your doctor should lower your tolterodine dose to 1 mg twice a day if you are taking these together. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Tolterodine or Clarithromycin based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.